There’s also strong evidence that mutual funds don’t outperform by successfully timing the market. For example, a study in the Spring/Summer 2009 issue of Vanguard Investment Perspectives examined the performance of mutual funds in bear markets. Defining a bear market as a loss of at least 10%, the study covered the period 1970 through 2008. The period included seven bear markets in the U.S. and six in Europe.

Once adjusting for risk (exposure to different asset classes), Vanguard’s researchers concluded that “whether an active manager is operating in a bear market, a bull market that precedes or follows it, or across longer-term market cycles, the combination of cost, security selection, and market-timing proves a difficult hurdle to overcome.”

They also confirmed that “past success in overcoming this hurdle does not ensure future success.” Vanguard was able to reach this conclusion despite the fact that the data was biased in favor of active managers because it contained survivorship bias.

Failing those two tests, can active managers perhaps outperform by successfully timing their exposures to factors that have been found to provide premiums over the long term? The idea is tempting, because the evidence shows that factor premiums are time-varying and regime-dependent.

For example, Arnav Sheth and Tee Lim’s December 2017 study “Fama-French Factors and Business Cycles” examined the behavior of six Fama-French factors—market beta (MKT), size (SMB), value (HML), momentum (MOM), investment (CMA) and profitability (RMW)—across business cycles, splitting them into four separate stages: recession, early-stage recovery, late-stage recovery and very-late stage-recovery. Their data, including the results shown in the following table, covered the period April 1953 through September 2015.

As you can see, factor premiums vary and are regime-dependent. That, of course, makes timing them tempting. In their September 2017 paper “How Can 'Smart Beta' Go Horribly Wrong?”, Research Affiliate’s Robert Arnott, Noah Beck, Vitali Kalesnik and John West advocate using risk factors’ value spread as a signal to time them, which begs the question of whether timing factors has been a successful strategy for actively managed funds.